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<p>[QUOTE=&quot;physics-fan3.14, post: 2218455, member: 19165&quot;]Bowl Luster is not a term that I&#039;ve ever heard - I agree that it sounds like a made up thing.</p><p><br /></p><p>Just a clarification on some of the other posts - all dies are basined. There is a curvature to the fields of every coin. Some are very shallow (almost all modern coins), and some are very deep (for example, Buffalos). However, there is a curvature to every die, and thus every coin.</p><p><br /></p><p>This is done primarily for 2 reasons: 1.) The curvature serves an artistic purpose to highlight the elements of the coin. By making the fields curved, you can make some of the devices stand out more and create a greater contrast than with flat fields.</p><p><br /></p><p>2.) The shape of the die will direct the flow of metal. You want the center of the die to strike the coin first, which will direct the metal outwards. For this reason, the high point of the die (that is, the lowest point on a coin) is going to be the center. There will be a gradual curvature outward to ensure the metal flows outward.</p><p><br /></p><p>And a correction to another post - coins with basining will absolutely have cartwheel luster. The basining refers to the shape of the die, and the cartwheel is created by the flow of metal upon striking. Since the shape of the die directs the flow of metal, more or less basining will change the appearance of luster, but all die-struck coins experience cold flow, and will thus all show luster. The effect that heavycam is referring to sounds like an exhausted die, or a clashed and repolished die, in which case the texture of the luster will appear differently.[/QUOTE]</p><p><br /></p>

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